Friday, November 19, 2010

Ages of ice samples found on the Earth cover a span approaching 200,000 years. Gas bubbles trapped in that ice can be used to learn about the composition of Earth's atmosphere at the time they were trapped in the ice. But how can we tell what the Earth's atmosphere was like before that?

Recently, USGS scientists have used a gas QMS to determine the oxygen level of ancient samples of Earth's atmosphere from a most unlikely place - amber. The fossilized resin of conifer trees, amber is interesting to scientists as a medium that traps insects, small animals, and plants, preserving them through geologic time for future study.

The recent extraction by scientists, of ancient DNA from organisms entombed in amber much like in the science-fiction novel and movie, Jurassic Park is an example of why scientists are intensely interested in amber. Minute bubbles of ancient air trapped by successive flows of tree resin during the life of the tree are preserved in the amber.

Analyses of the gases in these bubbles show that the Earth's atmosphere, 67 million years ago, contained nearly 35 percent oxygen compared to present levels of 21 percent. Results are based upon more than 300 analyses by USGS scientists of Cretaceous, Tertiary, and recent-age amber from 16 world sites.* The oldest amber in this study is about 130 million years old.

Wednesday, November 17, 2010

A new analysis of fossilized grass-pollen grains deposited on ancient European lake and sea bottoms 16-35 million years ago reveals that C4 grasses evolved earlier than previously thought. This new evidence casts doubt on the widely-held belief that the rise of this incredibly productive group of plants was driven by a large drop in atmospheric carbon dioxide concentrations during the Oligocene epoch.

The research team, led by University of Maryland Center for Environmental Science Appalachian Laboratory researcher Dr. David Nelson and University of Illinois Professor Feng Sheng Hu, examined the carbon isotope signatures of hundreds of grass-pollen grains and found that C4 grasses were already present on the landscape during the early part of the Oligocene, some 14 million years earlier than previously thought from geological evidence. Their findings are now published online in the journal Geology and will shortly appear in the print edition.

"The idea that C4 grasses originated prior to global decreases in carbon dioxide levels requires us to reevaluate the way we think about the evolution of C4 photosynthesis," said Dr. Nelson. "This new information should encourage the examination of alternate evolutionary selection pressures, such as warm temperatures or dry climates."

C4 plants compose only 3 percent of flowering plant species, yet account for about 25 percent global terrestrial productivity. About 60% of C4 species are grasses, and they dominate the world's grassland and savanna biomes, particularly those in warmer, lower latitude areas. Their ecological success results from the way these species concentrate and then fix carbon dioxide in order to power photosynthesis. While the most well known C4 plants are maize and sugar cane, both of which are critical to human consumption, there is a growing interest in their use as biofuels in order to capture carbon from the atmosphere to mitigate increasing global carbon dioxide levels.

The team used an innovative technique pioneered by Dr. Nelson earlier in his career - the Single Pollen Isotope Ratio Analysis or SPIRAL – to analyze the samples. The scientists first extracted grains of grass pollen from sedimentary rocks using a micromanipulator; then analyzed the tiny samples using a microcombustion device interfaced with an isotope ratio mass spectrometer in Ann Pearson's laboratory at Harvard University, which houses one of only a handful of these devices in the world. Through this analysis, they were able to detect the signature of C4 species from their more common C3 counterparts, because C4 and C3 plants take up different ratios of carbon isotopes during photosynthesis.

"SPIRAL enables us to detect C4 grasses at much lower abundances in geological records than previous approaches, which is helping to revolutionize our ability to study their ecology and evolution," said Dr. Hu. University of Illinois graduate student Michael Urban, lead author of the paper, continues to analyze samples from other parts of the world to look at variation in C4-grass abundance in relation to past changes in atmospheric CO2 and climate.

Physicists working at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, have succeeded in trapping antihydrogen – the antimatter equivalent of the hydrogen atom – a milestone that could soon lead to experiments on a form of matter that disappeared mysteriously shortly after the birth of the universe 14 billion years ago.

The first artificially produced low energy antihydrogen atoms – consisting of a positron, or antimatter electron, orbiting an antiproton nucleus – were created at CERN in 2002, but until now the atoms have struck normal matter and annihilated in a flash of gamma-rays within microseconds of creation.

The ALPHA (Antihydrogen Laser PHysics Apparatus) experiment, an international collaboration that includes physicists from the University of California, Berkeley, and Lawrence Berkeley National Laboratory (LBNL), has now trapped 38 antihydrogen atoms, each for more than one-tenth of a second.

While the number and lifetime are insufficient to threaten the Vatican – in the 2000 novel and 2009 movie "Angels & Demons," a hidden vat of potentially explosive antihydrogen was buried under St. Peter's Basilica in Rome – it is a starting point for learning new physics, the researchers said.

"We are getting close to the point at which we can do some classes of experiments on the properties of antihydrogen," said Joel Fajans, UC Berkeley professor of physics, LBNL faculty scientist and ALPHA team member. "Initially, these will be crude experiments to test CPT symmetry, but since no one has been able to make these types of measurements on antimatter atoms at all, it's a good start."

CPT (charge-parity-time) symmetry is the hypothesis that physical interactions look the same if you flip the charge of all particles, change their parity – that is, invert their coordinates in space – and reverse time. Any differences between antihydrogen and hydrogen, such as differences in their atomic spectrum, automatically violate CPT, overthrow today's "standard model" of particles and their interactions, and may explain why antimatter, created in equal amounts during the universe's birth, is largely absent today.

The team's results will be published online Nov. 17 in advance of its print appearance in the British journal Nature.

Climate change could trigger a 10 percent drop in China's grain harvest over the next 20 years, threatening the country's food security, a leading agriculture expert warned in comments published Friday.

Tang Huajun, deputy dean of the Chinese Academy of Agricultural Sciences, warned crop production could fall by five to 10 percent by 2030 if climate change continues unchecked, in an interview with the official China Daily.

"The output of the country's three main foods -- rice, wheat and corn -- may suffer a 37 percent decline in the latter part of this century if the government fails to take effective measures to address the impact of climate change," Tang was quoted as saying.

[...]

Tang is the chief scientist for a government project launched in September to study the impact of climate change on China's grain production over the past 20 years at 11 research stations in the north and south of the country.

"Agriculture has been the worst hit by climate change and some negative effects have become more obvious due to rising temperatures and water shortages over the past 10 years," Tang said.

Drought is the biggest threat to China's grain harvest, causing an annual average loss of 15 to 25 million tonnes from 1995 to 2005, or four to eight percent of the country's annual output, Tang said.

Noel. I am going to get to that 'How Bad Can It Get' post relatively soon. Maybe over Tday weekend. That said, I suspect 10% may be a little too conservative. Reason being that precipitation change is poorly predicted at this point, but is wildly different depending on the temperature range in models and almost always more negative for Australia, Central Asia and Africa.

A team of international researchers led by ancient DNA experts from the University of Adelaide has resolved the longstanding issue of the origins of the people who introduced farming to Europe some 8000 years ago.

A detailed genetic study of one of the first farming communities in Europe, from central Germany, reveals marked similarities with populations living in the Ancient Near East (modern-day Turkey, Iraq and other countries) rather than those from Europe.

Project leader Professor Alan Cooper, Director of the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, says: "This overturns current thinking, which accepts that the first European farming populations were constructed largely from existing populations of hunter-gatherers, who had either rapidly learned to farm or interbred with the invaders."

The results of the study have been published today in the online peer-reviewed science journal PLoS Biology.

"We have finally resolved the question of who the first farmers in Europe were – invaders with revolutionary new ideas, rather than populations of Stone Age hunter-gatherers who already existed in the area," says lead author Dr Wolfgang Haak, Senior Research Associate with ACAD at the University of Adelaide.

"We've been able to apply new, high-precision ancient DNA methods to create a detailed genetic picture of this ancient farming population, and reveal that it was radically different to the nomadic populations already present in Europe.

"We have also been able to use genetic signatures to identify a potential route from the Near East and Anatolia, where farming evolved around 11,000 years ago, via south-eastern Europe and the Carpathian Basin (today's Hungary) into Central Europe," Dr Haak says.

[...]

The ancient DNA used in this study comes from a complete graveyard of Early Neolithic farmers unearthed at the town of Derenburg in Saxony-Anhalt, central Germany.

No time. Seriously no time. Just trying to get back to doing this some.

Tuesday, November 02, 2010

A baby dinosaur approximately the size of a pug dog scurried alongside what may have been its mom or dad some 148 million years ago in what is now foothills near Denver, scientists reported today (Nov. 1) at the annual meeting of the Geological Society of America in Denver.

They caught the paleo-action in the footprints left behind there near the town of Morrison, Colo. The scientists think the dinosaur prints, a set of infant prints next to partial prints from an adult, belonged to Apatosaurus, a sauropod - giant, long-necked dinosaurs that preferred veggies - and once known as Brontosaurus.

As an adult, Apatosaurus is the largest dinosaur found in the Denver metro area, the researchers say, spanning a length of three school buses and weighing as much as eight Asian elephants.

The prints likely made by the infant Apatosaurus were tiny - if you were to place a mug over one, it would completely eclipse the print, according to one of the discoverers, Matthew Mossbrucker, director of the Morrison Natural History Museum in Boulder, Colo.

"The distance between each step is two times wider than what we observe in walking tracks, indicating the animal was at a low-speed run," Mossbrucker said. "I am not aware of any running sauropod tracks anywhere."

The trackway of running prints show only the hind paws, suggesting either that while the baby dinosaur was running, its hind paws eclipsed and removed the front paw track, or that the animal was running only on its hind paws. The tracks made by the adult in a walking mode did show a front paw print.

"We've been arguing for more than a century as to whether or not sauropods could stand up on their back paws," Mossbrucker told LiveScience. "Apparently they can, and the young can even run."

Mossbrucker notes that under the scientific definition of running, this little guy may not have met the criteria. But "if you were to see this animal scurry and scamper in front of you, you would say it's running," he said.

"In the end, we might have a baby sauropod that is running like a Basilisk lizard, a modern lizard that is mostly a quadroped, but when spooked it runs on its hindlegs," Mossbrucker said.

Friday, October 29, 2010

China has officially built the world's faster computer. This is impressive. Most people have been saying that its all built from US parts. There is some truth to that. The CPUs and whatnot are nvidia GPUs and CPUs (AMD?) are US $tech.

However, the ever important interconnect is NOT American. This is homegrown and that is really impressive. Interconnects are hard. its also rumored to be twice as fast as QDR infiniband and laid out as a fat tree. its also rumored to use around 14 MW. That's excellent.

This has been compared to what the Japanese did with the Earth Simulator. That claimed the top spot for some time because it was around 4x+ faster than the US counterparts. The difference here between Tinhe-1A and the US counterparts is not that much, in comparison: 50%. I would expect this machine to be overtaken in a year at most. Possibly by June.

Congratulations to the Chinese. I wish I were going to SC10 now. Its sure to be an exciting event now. we'll see if the US can pull out any surprise benchmarks now. Never know. I doubt it though.

The giant dragonflies of ancient Earth with wingspans of up to 70 centimeters (28 inches) are generally attributed to higher oxygen atmospheric levels in the atmosphere in the past. New experiments in raising modern insects in various oxygen-enriched atmospheres have confirmed that dragonflies grow bigger with more oxygen, or hyperoxia.

However, not all insects were larger when oxygen was higher in the past. For instance, the largest cockroaches ever are skittering around today. The question becomes how and why do different groups respond to changes in atmospheric oxygen.

The secrets to why these changes happened may be in the hollow tracheal tubes insects use to breathe. Getting a better handle on those changes in modern insects could make it possible to use fossilized insects as proxies for ancient oxygen levels.

"Our main interest is in how paleo-oxygen levels would have influenced the evolution of insects," said John VandenBrooks of Arizona State University in Tempe. To do that they decided to look at the plasticity of modern insects raised in different oxygen concentrations. The team raised cockroaches, dragonflies, grasshoppers, meal worms, beetles and other insects in atmospheres containing different amounts of oxygen to see if there were any effects.

One result was that dragonflies grew faster into bigger adults in hyperoxia. However, cockroaches grew slower and did not become larger adults. In all, ten out of twelve kinds of insects studied decreased in size in lower oxygen atmospheres. But there were varied responses when they were placed into an enriched oxygen atmosphere. VandenBrooks will be presenting the results of the work on Monday, Nov. 1 at the annual meeting of the Geological Society of America in Denver.

"The dragonflies were the most challenging of the insects to raise," said VandenBrooks because, among other things, there is no such thing as dragonfly chow. As juveniles they need to hunt live prey and in fact undergraduate students Elyse Muñoz and Michael Weed working with Dr. VandenBrooks had to resort to hand feeding the dragonflies daily.

"Dragonflies are notoriously difficult to rear," said VandenBrooks. "We are one of the only groups to successfully rear them to adulthood under laboratory conditions."

Once they had worked that out, however, they raised three sets of 75 dragonflies in atmospheres containing 12 percent (the lowest oxygen has been in the past), 21 percent (like modern Earth's atmosphere) and 31 percent oxygen (the highest oxygen has been).

Cockroaches, as anyone who has fought them at home knows, are much easier to rear. That enabled the researchers to raise seven groups of 100 roaches in seven different atmospheres ranging from 12 percent to 40 percent oxygen mimicking the range of paleo-oxygen levels. Cockroaches took about twice as long to develop in high oxygen levels.

"It is the exact opposite of what we expected," said VandenBrooks. One possibility is that the hyperoxic reared roaches stayed in their larval stage longer, perhaps waiting for their environment to change to a lower, maybe less stressful oxygen level.

This surprising result prompted the researchers to take a closer look at the breathing apparatus of roaches – their tracheal tubes. These are essentially hollow tubes in an insect's body that allow gaseous oxygen to enter directly into the insect tissues.

VandenBrooks and his team took their hyperoxic reared roaches to Argonne National Lab's x-ray synchrontron imaging facility to get a closer look at the tracheal tubes. The x-ray synchrontron is particularly good at resolving the edges where things of different phases meet – like solids on liquids or gas on solids. That's just what the inside of a tracheal tube is.

What they found was that the tracheal tubes of hyperoxic reared roaches were smaller than those in lower oxygen atmospheres. That decrease in tube size with no increase in the overall body size would allow the roaches to possibly invest more in tissues used for other vital functions other than breathing – like eating or reproducing. The roaches reared in hypoxia (lower oxygen) would have to trade off their investment in these other tissues in order to breathe.

The next step, said VandenBrooks, will be to look closely at the tracheal tubes of insects fossilized in amber to see what they might say about oxygen levels at various times in the past. These might possibly serve as a proxy for paleo-oxygen levels.

More than two and a half billion years ago, Earth differed greatly from our modern environment, specifically in respect to the composition of gases in the atmosphere and the nature of the life forms inhabiting its surface. While today's atmosphere consists of about 21 percent oxygen, the ancient atmosphere contained almost no oxygen. Life was limited to unicellular organisms. The complex eukaryotic life we are familiar with – animals, including humans – was not possible in an environment devoid of oxygen.

The life-supporting atmosphere Earth's inhabitants currently enjoy did not develop overnight. On the most basic level, biological activity in the ocean has shaped the oxygen concentrations in the atmosphere over the last few billion years. In a paper published today by Nature Geoscience online, Arizona State University researchers Brian Kendall and Ariel Anbar, together with colleagues at other institutions, show that "oxygen oases" in the surface ocean were sites of significant oxygen production long before the breathing gas began to accumulate in the atmosphere.

By the close of this period, Earth witnessed the emergence of microbes known as cyanobacteria. These organisms captured sunlight to produce energy. In the process, they altered Earth's atmosphere through the production of oxygen – a waste product to them, but essential to later life. This oxygen entered into the seawater, and from there some of it escaped into the atmosphere.

"Our research shows that oxygen accumulation on Earth first began to occur in surface ocean regions near the continents where the nutrient supply would have been the highest," explains Kendall, a postdoctoral research associate at the School of Earth and Space Exploration in ASU's College of Liberal Arts and Sciences. "The evidence suggests that oxygen production in the oceans was vigorous in some locations at least 100 million years before it accumulated in the atmosphere. Photosynthetic production of oxygen by cyanobacteria is the simplest explanation."

The idea of "oxygen oases," or regions of initial oxygen accumulation in the surface ocean, was hypothesized decades ago. However, it is only in the past few years that compelling geochemical evidence has been presented for the presence of dissolved oxygen in the surface ocean 2.5 billion years ago, prior to the first major accumulation of oxygen in the atmosphere (known as the Great Oxidation Event).

Kendall's work is the latest in a series of recent studies by a collaborative team of researchers from ASU; University of California, Riverside; and University of Maryland that point to the early rise of oxygen in the oceans. Together with colleagues from University of Washington and University of Alberta, this team first presented evidence for the presence of dissolved oxygen in these oceans in a series of four Science papers over the past few years. These papers focused on a geologic formation called the Mt. McRae Shale from Western Australia. One of these papers, led by the ASU team, presented geochemical profiles that showed an abundance of two redox-sensitive elements – rhenium (Re) and molybdenum (Mo) – implying that small amounts of oxygen mobilized these metals from the crust on land or in the ocean, and transport them through an oxic surface ocean to deeper anoxic waters where the metals were hidden into organic-rich sediments. Kendall participated in this research while a postdoctoral student at the University of Alberta.

Kendall's goal in the new project was to look for evidence of dissolved oxygen in another location. He wanted to see if the geochemical evidence from the Mt. McRae Shale in Western Australia would be found in similarly-aged rocks from South Africa. Those rocks were obtained in a project supported by the Agouron Institute. Kendall's research was supported by grants from NASA and the National Science Foundation.

What Kendall discovered was a unique relationship of high rhenium and low molybdenum enrichments in the samples from South Africa, pointing to the presence of dissolved oxygen on the seafloor itself.

"In South Africa, samples from the continental slope beneath the shallower platform were thought to be deposited at water depths too deep for photosynthesis. So it was a big surprise that we found evidence of dissolved oxygen on the seafloor at these depths. This discovery suggests that oxygen was produced at the surface in large enough quantities that some oxygen survived as it was mixed to greater depths. That implies a significantly larger amount of oxygen production and accumulation in 'oxygen oases' than was previously realized."

A key contribution to this study came from Christopher Reinhard and Timothy Lyons, collaborators at the University of California, Riverside, and Simon Poulton at Newcastle University, who found that the chemistry of iron (Fe) in the same shales is also consistent with the presence of dissolved oxygen.

"It was especially satisfying to see two different geochemical methods – rhenium and molybdenum abundances and Fe chemistry – independently tell the same story," Kendall noted.

Evidence that the atmosphere contained at most minute amounts of oxygen came from measurements of the relative abundances of sulfur (S) isotopes. These measurements were performed by Alan Kaufman, a collaborator at the University of Maryland.

New research from the Centre for Addiction and Mental Health (CAMH) and The Hospital for Sick Children (SickKids), both in Toronto, Canada provides further clues as to why Autism Spectrum Disorder (ASD) affects four times more males than females. The scientists discovered that males who carry specific alterations of DNA on the sole X-chromosome they carry are at high risk of developing ASD. The research is published in the September 15 issue of Science Translational Medicine.

ASD is a neurological disorder that affects brain functioning, resulting in challenges with communication and social interaction, unusual patterns of behaviour, and often, intellectual deficits. ASD affects one in every 120 children and a startling one in 70 boys. Though all of the causes of ASD are not yet known, research has increasingly pointed towards genetic factors,. In recent years, several genes involved in ASD have successfully been identified.

The research team was led by Dr. John B. Vincent, Senior Scientist and head of CAMH's Molecular Neuropsychiatry and Development Laboratory and Dr. Stephen Scherer, Senior Scientist and Director of The Centre for Applied Genomics at SickKids, and Director of the McLaughlin Centre at the University of Toronto. The scientists analyzed the gene sequences of 2,000 individuals with ASD, along with others with an intellectual disability, and compared the results to thousands of population controls. They found that about one per cent of boys with ASD had mutations in the PTCHD1 gene on the X-chromosome. Similar mutations were not found in thousands of male controls. Also, sisters carrying the same mutation are seemingly unaffected.

"We believe that the PTCHD1 gene has a role in a neurobiological pathway that delivers information to cells during brain development – this specific mutation may disrupt crucial developmental processes, contributing to the onset of autism." said Dr. Vincent. "Our discovery will facilitate early detection, which will, in turn, increase the likelihood of successful interventions."

"The male gender bias in autism has intrigued us for years and now we have an indicator that starts to explain why this may be," says Dr. Scherer. "Boys are boys because they inherit one X-chromosome from their mother and one Y-chromosome from their father. If a boy's X-chromosome is missing the PTCHD1 gene or other nearby DNA sequences, they will be at high risk of developing ASD or intellectual disability. Girls are different in that, even if they are missing one PTCHD1 gene, by nature they always carry a second X-chromosome, shielding them from ASD." Scherer adds, "While these women are protected, autism could appear in future generations of boys in their families."

There was a relatively recent study that found that autism was more common in affluent caucasian families with older parents. It went rather contrary to the environmental causes hypothesis. If I have time (HA!) I'll find and put a link to that one.

It makes me wonder if this can be directly linked to postponing having kids: we already know of increased rates of other issues such as down's and whatnot. Perhaps the damage is being caused by meiosis potentially going slightly off tracks in (some) older women. As more women postpone their fertility, the number of autistic children rises and will continue to do for generations afterwards because their daughters might be carriers of the damaged regions on their inherited X chromosomes.

I can't imagine that this will be a popular study result or my hypothesis either.

A team of scientists, led by biogeochemists at the University of California, Riverside, has found new evidence linking "Snowball Earth" glacial events to the rise of early animals.

The controversial Snowball Earth hypothesis posits that the Earth was covered from pole to pole by a thick sheet of ice lasting, on several occasions, for millions of years. These glaciations, the most severe in Earth history, occurred from 750 to 580 million years ago. The researchers argue that the oceans in the aftermath of these events were rich in phosphorus, a nutrient that controls the abundance of life in the oceans.

The UC Riverside team and colleagues tracked phosphorus concentrations through Earth's history by analyzing the composition of iron-rich chemical precipitates that accumulated on the seafloor and scavenged phosphorus from seawater. Their analyses revealed that there was a pronounced spike in marine phosphorus levels in the mid-Neoproterozoic (from ~750 to ~635 million years ago).

To explain these anomalously high concentrations, the researchers argue that the increase in erosion and chemical weathering on land that accompanied Snowball Earth glacial events led to the high amounts phosphorus in the ocean. The abundance of this nutrient, which is essential for life, in turn, led to a spike in oxygen production via photosynthesis and its accumulation in the atmosphere, facilitating the emergence of complex life on Earth.

Study results appear in the Oct. 28 issue of Nature.

"In the geological record, we found a signature for high marine phosphorus concentrations appearing in the immediate aftermath of the Snowball Earth glacial events," said Noah Planavsky, the first author of the research paper and a graduate student in the Department of Earth Sciences. "Phosphorus ultimately limits net primary productivity on geological timescales. Therefore, high marine phosphorus levels would have facilitated a shift to a more oxygen-rich ocean-atmosphere system. This shift could have paved the way for the rise of animals and their ecological diversification. Our work provides a mechanistic link between extensive Neoproterozoic glaciations and early animal evolution."

Planavsky explained the link between marine phosphorus concentrations and the levels of oxygen in the atmosphere.

"High phosphorus levels would have increased biological productivity in the ocean and the associated production of oxygen by photosynthesis," he said. "Much of this organic matter is consumed, in turn, as a result of respiration reactions that also consume oxygen. However, the burial of some proportion of the organic matter results in a net increase of oxygen levels in the atmosphere."

Until now, scientists believed that geochemical conditions in the iron-rich ocean would have led to low phosphorus concentrations. The UC Riverside researchers found no evidence of a phosphorus crisis after Snowball Earth glacial events, however, finding instead indications of an abundance of phosphorus.

Scientists have discovered in China the first complete skeleton of a pivotal ancestor of Earth's largest land animals – the sauropod dinosaurs. The new species, tentatively dubbed Yizhousaurus sunae, lived on the flood plains around Lufeng in the Yunnan Province of South China about 200 million years ago. The species helps explain how the iconic four-footed, long-necked sauropod dinosaurs evolved.

Unlike the 120-foot-long, 100-ton sauropod giants that came later, Yizhousaurus was about 30 feet in length, but it shows all of the hallmarks of later sauropods: the beginning of a long neck, a robust skeleton and four-legged posture. It also comes with an intact fossilized skull – which is very rare and crucial for understanding its place in the evolution of sauropods.

"Sauropods have these big bones but their skulls are very lightly constructed and also very small," said paleontologist Sankar Chatterjee of Texas Tech University. Chatterjee presents the discovery on Sunday, Oct. 31 at the annual meeting of the Geological Society of America in Denver.

Yizhousaurus's skull is broad, high and domed, less than a foot long with a short snout, eye sockets on the sides for scanning enemies. It has an unusually wide and U-shaped jaw, in top view, like that seen in later Camarasaurus, said Chatterjee. Numerous serrated and spoon-shaped teeth of the upper and lower jaws would shear and slide past each other for cutting plant material during feeding. The sturdy teeth and raised neck let the animal very easily nip small branches from treetops and then chew the plant material.

Wednesday, October 06, 2010

The oldest evidence of the dinosaur lineage—fossilized tracks—is described this week in Proceedings of the Royal Society B. Just one or two million years after the massive Permian-Triassic extinction, an animal smaller than a house cat walked across fine mud in what is now Poland. This fossilized trackway places the very closest relatives of dinosaurs on Earth about 250 million years ago—5 to 9 million years earlier than previously described fossilized skeletal material has indicated. The paper also described the 246-million-year-old Sphingopus footprints, the oldest evidence of a bipedal and large-bodied dinosaur.

"We see the closest dinosaur cousins immediately after the worst mass extinction," says Stephen Brusatte, a graduate student affiliated with the Division of Paleontology at the American Museum of Natural History. "The biggest crisis in the history of life also created one of the greatest opportunities in the history of life by emptying the landscape and making it possible for dinosaurs to evolve."

The new paper analyzes three sets of footprints from three different sites in the Holy Cross Mountains of central Poland. The sites, all quarries within a 25-mile radius of each other, are windows into three ecosystems because they represent different times periods. The Stryczowice trackway is the oldest at 250 million years. The Baranów trackway is the most recent at 246 million years of age while the Wióry trackway is sandwiched in time between the others.

Because footprints are only an imprint of a small part of the skeleton, identification of trackmakers is often tricky. Luckily, dinosaurs have a very distinctive gait, especially when compared to their diapsid relatives (the evolutionary group that includes birds, reptiles, and extinct lineages) like crocodiles and lizards. While lizards and crocodiles have a splayed walking style, dinosaurs place their two feet closer together. The footprints at all three Polish sites show this feature as well as indisputable dinosaur-like features, including three prominent central toes and reduced outer two toes, a parallel alignment of these three digits (a bunched foot), and a straight back edge of footprints, additional evidence of a dinosaur-like simple hinged ankle.

Because all of these features are seen in footprints at the oldest site, Brusatte and colleagues conclude that the Stryczowice prints—which are only a few centimeters in length—are the oldest evidence of the dinosaur lineage. These dinosaurs, though, are considered "stem dinosaurs," or the immediate relatives of dinosaurs not part of the slightly more derived clade that technically defines dinosaurs. Also, this animal did walk on all four limbs, an abnormal posture for early dinosaurs and their close relatives, although it appears that its forelimbs were already being reduced to more dinosaur-like proportions since the footprints overstep handprints.

The Baranów and Wióry trackways show changes early in the evolutionary history of dinosaurs. Wióry at 248 million years ago shows slight diversification in the types of tracks, but all tracks remain quadrupedal. Footprints from Baranów at 246 million years ago, however, may be the earliest evidence of moderately large-bodied and bipedal true dinosaurs. These tracks, which are called Sphingopus, are 15 centimeters long.

C. corcovatus's hump possibly supported a mound of fleshy tissue storing fat, as on a camel, according to the study team, led by paleontologist Francisco Ortega of the Universidad Nacional de Educacíon a Distancia in Madrid.

Alternatively, the hump might have had a display role—for example, attracting a mate or intimidating rivals—or may have helped diffuse heat and regulate body temperature, Ortega said.

I refuse to call it a camelsaur.

So, being a carcharodontosaurid spread to likely point that quills if not feathers evolved, right?

Thursday, September 02, 2010

Computational scientists and geophysicists at the University of Texas at Austin and the California Institute of Technology (Caltech) have developed new computer algorithms that for the first time allow for the simultaneous modeling of the earth's mantle flow, large-scale tectonic plate motions, and the behavior of individual fault zones, to produce an unprecedented view of plate tectonics and the forces that drive it.

A paper describing the whole-earth model and its underlying algorithms will be published in the August 27 issue of the journal Science and also featured on the cover.

The work "illustrates the interplay between making important advances in science and pushing the envelope of computational science," says Michael Gurnis, the John E. and Hazel S. Smits Professor of Geophysics, director of the Caltech Seismological Laboratory, and a coauthor of the Science paper.

To create the new model, computational scientists at Texas's Institute for Computational Engineering and Sciences (ICES)—a team that included Omar Ghattas, the John A. and Katherine G. Jackson Chair in Computational Geosciences and professor of geological sciences and mechanical engineering, and research associates Georg Stadler and Carsten Burstedde—pushed the envelope of a computational technique known as Adaptive Mesh Refinement (AMR).

Partial differential equations such as those describing mantle flow are solved by subdividing the region of interest (such as the mantle) into a computational grid. Ordinarily, the resolution is kept the same throughout the grid. However, many problems feature small-scale dynamics that are found only in limited regions. "AMR methods adaptively create finer resolution only where it's needed," explains Ghattas. "This leads to huge reductions in the number of grid points, making possible simulations that were previously out of reach.”

"The complexity of managing adaptivity among thousands of processors, however, has meant that current AMR algorithms have not scaled well on modern petascale supercomputers," he adds. Petascale computers are capable of one million billion operations per second. To overcome this long-standing problem, the group developed new algorithms that, Burstedde says, "allows for adaptivity in a way that scales to the hundreds of thousands of processor cores of the largest supercomputers available today."

With the new algorithms, the scientists were able to simulate global mantle flow and how it manifests as plate tectonics and the motion of individual faults. According to Stadler, the AMR algorithms reduced the size of the simulations by a factor of 5,000, permitting them to fit on fewer than 10,000 processors and run overnight on the Ranger supercomputer at the National Science Foundation (NSF)-supported Texas Advanced Computing Center.

A key to the model was the incorporation of data on a multitude of scales. "Many natural processes display a multitude of phenomena on a wide range of scales, from small to large," Gurnis explains. For example, at the largest scale—that of the whole earth—the movement of the surface tectonic plates is a manifestation of a giant heat engine, driven by the convection of the mantle below. The boundaries between the plates, however, are composed of many hundreds to thousands of individual faults, which together constitute active fault zones. "The individual fault zones play a critical role in how the whole planet works," he says, "and if you can't simulate the fault zones, you can't simulate plate movement"—and, in turn, you can't simulate the dynamics of the whole planet.

In the new model, the researchers were able to resolve the largest fault zones, creating a mesh with a resolution of about one kilometer near the plate boundaries. Included in the simulation were seismological data as well as data pertaining to the temperature of the rocks, their density, and their viscosity—or how strong or weak the rocks are, which affects how easily they deform. That deformation is nonlinear—with simple changes producing unexpected and complex effects.

"Normally, when you hit a baseball with a bat, the properties of the bat don't change—it won't turn to Silly Putty. In the earth, the properties do change, which creates an exciting computational problem," says Gurnis. "If the system is too nonlinear, the earth becomes too mushy; if it's not nonlinear enough, plates won't move. We need to hit the 'sweet spot.'"

After crunching through the data for 100,000 hours of processing time per run, the model returned an estimate of the motion of both large tectonic plates and smaller microplates—including their speed and direction. The results were remarkably close to observed plate movements.

Wednesday, September 01, 2010

With the impending retirement of NASA's space shuttle fleet, aerospace juggernaut Boeing is hard at work developing a new capsule-based spaceship that could be ready for its first commercial spaceflight by 2015.

Boeing's new Crew Space Transportation-100 spacecraft is designed to fly astronauts to and from the International Space Station (ISS), as well as future private space stations.

Keith Reiley, Boeing's commercial crew development program manager, will be presenting updates on the Commercial Crew Transportation System at the American Institute of Aeronautics and Astronautic Space 2010 Conference and Exposition next week in Anaheim, Calif.

As one of the leading suppliers of human space systems and services, Boeing already has a strong heritage in the industry. [Video: Boeing's New Spacecraft]

"It was an enormous advantage," Reiley told SPACE.com. "A lot of the equipment we're looking at has ISS heritage. About half of our team were designers that came from ISS and had experience with the flight hardware. The other half were space shuttle designers."

To help reach its goal, the company looked to existing facilities, launchers and proven processes to ensure safety, lower development costs and reduce overall risk.

Boeing's CST-100 spacecraft is approximately 15 feet (4.5 meters) wide and can carry up to seven people. The cone-shaped capsule will look similar to NASA's Apollo and Orion spacecraft.

Boeing settled on the cone-shaped design because it was thought to be the safest and most inexpensive of the vehicle concepts that were considered, Reiley said.

The spacecraft is being designed for compatibility with a variety of rockets, including United Launch Alliance's Atlas and Delta boosters and SpaceX's Falcon rockets. This will give Boeing the flexibility to select an appropriate rocket later in the development process.

The spacecraft will also be equipped with a unique pusher abort system in case the crew encounters an emergency during launch.

"This is the first time anyone has proposed or succeeded with a pusher design," Reiley said. "The pusher appears, to us, to be simpler, less expensive and just as safe."

If necessary, the launch abort system would fire pressurized propellant for three seconds to quickly push the vehicle away from the rocket. A parachute would then be deployed to assist with the landing.

One of the advantages of the pusher design is that in the event of a smooth launch, the same propellant can also be used on orbit, either in guiding the CST-100 to dock with a space station, or to boost stations themselves, whose orbits slowly decay over time.

"You get the ability to use the propellant to re-boost our customer stations or simply for orbital maneuvering to get there," Reiley said. "In order to catch up with the station you're trying to rendezvous with, you have to boost yourself up to the station's orbit, and all that takes a certain amount of fuel."

For Boeing, one of their main challenges in expanding their branch of commercial spaceflight is in designing a relatively inexpensive option.

The company has set a design requirement that the CST-100 be reusable up to 10 times. The exact number of times the capsule is reused, however, will depend upon inspection after touchdown.

Monday, August 30, 2010

By describing a new double-clawed and highly-unusual relative of Velociraptor, paleontologists have answered a long-standing question: what did the Late Cretaceous predatory dinosaurs in Europe look like? Balaur bondoc, described this week in Proceedings of the National Academy of Sciences, is the first reasonably complete skeleton of a meat-eating dinosaur from the final 60 million years of the Age of Dinosaurs in Europe and provides insight into an ecosystem very different from that of today. Europe at the end of the Cretaceous was awash in higher seas and was an island archipelago dominated by animals smaller and more primitive than their relatives living on larger landmasses.

"We've all been waiting for something like this, and the wait has yielded an interesting surprise," says Mark Norell, chair of the Division of Paleontology at the American Museum of Natural History and one of the authors of the research paper describing the fossil. "B. bondoc is heavy, with unexpectedly stocky limbs and fused bones. It shows just how unusual the fauna of the area was during the waning years of the dinosaur era."

"Balaur might be one of the largest predators in this ecosystem because not even a big tooth has been found in Romania after over a hundred years of research," says co-author Zoltán Csiki of the University of Bucharest. "Fragmentary remains of Balaur were already known for more than 10 years, but the morphology is so weird we didn't have any idea where to fit them."

Balaur bondoc, which means "stocky dragon," was unearthed in Romania by geologist and co-author Mátyás Vremir of the Transylvanian Museum Society. Higher sea levels at the end of the Cretaceous flooded much of present-day continental Europe, so Romania, which was an island, is now one of the best windows into Europe at the end of the Age of Dinosaurs. Other fossils discovered in these deposits include dwarf sauropods that were the size of cows and tiny duck-billed dinosaurs.

[...]

The new theropod fossil, the type specimen, is a partial skeleton that includes leg, hip, backbone, arms, hand, rib, and tail bones. But B. bondoc has 20 unique features when compared to its nearest relatives, including a re-evolved functional big toe with a large claw that can be hyperextended, presumably used to slash prey. Because there is also a large claw on the second toe, as is typical of the group of dinosaurs to which B. bondoc belongs, the new species has unusual double-clawed feet. Unique features are also found in other parts of the foot, leg, and pelvis. The feet and legs are short and stocky, with bones fused together, and the pelvis has enormous muscle attachment areas, indicating that this species was adapted for strength over speed. Finally, the hand is atrophied and some of the bones are fused, features that would have made grasping difficult. This, in combination with the leg and foot traits, indicates that the lower limbs rather than hands were used to grasp and disembowel prey.

"Balaur is a new breed of predatory dinosaur, very different from anything we have ever known," says Stephen Brusatte, a graduate student at Columbia University who is affiliated with the Museum. "Its anatomy shows that it probably hunted in a different way than its less stocky relatives. Compared to Velociraptor, Balaur was probably more of a kickboxer than a sprinter, and it might have been able to take down larger animals than itself, as many carnivores do today."

"Nevertheless, Balaur is the size of an oversized turkey and unlike what we know of the large predators from other parts of the world at the same time period, like Tyrannosaurus or Carnotaurus," says Csiki. "As European dinosaur faunas were known to be peculiar, we half-expected to find peculiar predators as well. But, as the first good record of these, Balaur surely exceeds our most daring expectations."

Wednesday, August 25, 2010

The ancient "terror bird" Andalgalornis couldn't fly, but it used its unusually large, rigid skull--coupled with a hawk-like hooked beak--in a fighting strategy reminiscent of boxer Muhammad Ali.

The agile creature repeatedly attacked and retreated, landing well-targeted, hatchet-like jabs to take down its prey, according to results of a new study published this week in the journal PLoS ONE.

The study is the first detailed look at the predatory style of a member of an extinct group of large, flightless birds known scientifically as Phorusrhacids but popularly labeled "terror birds" because of their fearsome skull and often imposing size.

Terror birds evolved about 60 million years ago in isolation in South America, an island continent until the last few million years, radiating into about 18 known species ranging in size up to the 7-foot-tall (2.1 meters) Kelenken.

Because terror birds have no close analogs among modern-day birds, their life habits have been shrouded in mystery, according to William Zamer, acting deputy director of the National Science Foundation (NSF)'s Division of Integrative Organismal Systems, which funded the research.

Now, a multinational team of scientists has performed the most sophisticated study to date of the form, function and predatory behavior of a terror bird, using CT scanning and advanced engineering methods.

"No one has ever attempted such a comprehensive biomechanical analysis of a terror bird," said study lead author Federico Degrange of the Museo de La Plata/CONICET in Argentina.

"We need to figure out the ecological role these amazing birds played if we really want to understand how the unusual ecosystems of South America evolved over the past 60 million years."

The terror bird under study is called Andalgalornis and lived in northwestern Argentina about six million years ago. It was a mid-sized terror bird, standing about 4.5 feet tall (1.4 meters) and weighing in at a fleet-footed 90 pounds (40 kg).

Like all terror birds, its skull was relatively enormous (14.5 inches or 37 centimeters) with a deep narrow bill armed with a powerful, hawk-like hook.

Paper co-author Lawrence Witmer of the Ohio University College of Osteopathic Medicine ran a complete skull of Andalgalornis through a CT scanner, giving the team a glimpse into the skull's inner architecture.

The scans revealed to Witmer, Degrange and article co-author Claudia Tambussi, also from the Museo de La Plata/CONICET, that Andalgalornis was unlike other birds because it had evolved a highly rigid skull.

"Birds generally have skulls with lots of mobility between the bones, which allows them to have light but strong skulls," said Witmer.

"But we found that Andalgalornis had turned these mobile joints into rigid beams. This guy had a strong skull, particularly in the fore-aft direction, despite having a curiously hollow beak."

The evolution of this large and rigid bony weapon was presumably linked to the loss of flight in terror birds, as well as to their sometimes gigantic sizes.

From the CT scans, Stephen Wroe, director of the Computational Biomechanics Research Group at the University of New South Wales, Australia, assembled sophisticated 3-D models of the terror bird and two living species for comparison (an eagle, and the terror bird's closest living relative, the seriema).

Using computers and software supplied by Wroe, Degrange and Karen Moreno of the Université Paul Sabatier in Toulouse, France, applied an approach known as Finite Element Analysis to simulate and compare the biomechanics of biting straight down (as in a killing bite), pulling back with its neck (as in dismembering prey) and shaking the skull from side to side (as in thrashing smaller animals, or when dealing with larger struggling prey).

Color images created by the program show cool-blue areas where stresses are low and white-hot areas where stresses get dangerously high.

The simulations supported the CT-based anatomical results.

"Relative to the other birds considered in the study, the terror bird was well-adapted to drive the beak in and pull back with that wickedly recurved tip of the beak," remarked Wroe, "but when shaking its head from side to side, its skull lights up like a Christmas tree."

A key part of the analysis was determining how hard a bite Andalgalornis could deliver.

To examine bite force in birds in general, Degrange and Tambussi worked with zookeepers at the La Plata Zoo to get a seriema and an eagle to chomp down on their bite meter.

"We discovered that the bite force of Andalgalornis was a little lower than we expected, and weaker than the bite of many carnivorous mammals of about the same size," Degrange said.

"Andalgalornis may have compensated for this weaker bite by using its powerful neck muscles to drive its strong skull into prey like an axe."

The team's results give new insight into the lifestyle of a unique avian predator.

Its skull, though strong vertically, was weak from side to side; its hollow beak was in danger of catastrophic fracture if Andalgalornis grappled too vigorously with large struggling prey.

Instead, the study shows that the terror bird engaged in an elegant style more like that of Muhammad Ali--a repeated attack-and-retreat strategy with well-targeted, hatchet-like jabs.

Once killed, the prey would have been ripped into bite-sized morsels by the powerful neck pulling the head straight back or, if possible, swallowed whole.

A modern-day space race to land an unmanned probe on the Moon is emerging between Russia and India on one side and China on the other.

After months of negotiations, Russian and Indian engineers have started working on a robotic mission together.

This would see the landing of a small four-wheeled rover on to the surface of the Earth's celestial neighbour.

It is set to launch in 2013, to roughly match the scheduled lunar landing of China's Chang'e-3 spacecraft.

Whichever team gets there first, it would be the first human hardware to function on the lunar surface since the Soviet Luna-24 spacecraft returned to Earth with Moon's soil samples in 1976.

Known in Russia as Luna-Resource and in India as Chandrayaan-2, the joint mission will include an Indian-built lunar orbiter and the Russian-built landing platform both launched by a single Indian rocket.

The Russian-built four-legged platform will deliver around 35kg of scientific equipment to the lunar surface and release a 15kg Indian-built robotic rover.

Despite being a far cry from the 750kg Soviet Lunokhod rovers, which rolled across the lunar landscape in the 1970s, the tiny Indian electric vehicle is still expected to provide scientific data, thanks to miniaturisation of technology.

"We do understand that, first of all, it is a demonstration of the Indian presence on the surface of the Moon," Aleksandr Zakharov, a leading scientist at the Space Research Institute (IKI) in Moscow told BBC News.

"However, it will have a TV camera onboard, and we also asked our Indian partners to include a miniature manipulator, so it could sample soil beyond the reach of the robotic arm of the (stationary Russian) lander."

The rover and all of its scientific instruments are expected to be Indian-built, even though India is free to solicit foreign participation, Mr Zakharov said.

Fossils of what could be the oldest animal bodies have been discovered in Australia, pushing back the clock on when animal life first appeared on Earth to at least 70 million years earlier than previously thought.

The results suggest that primitive sponge-like creatures lived in ocean reefs about 650 million years ago. Digital images of the fossils suggest the animals were about a centimeter in size (the width of your small fingertip) and had irregularly shaped bodies with a network of internal canals.

The shelly fossils, found beneath a 635 million-year-old glacial deposit in South Australia, represent the earliest evidence of animal body forms in the current fossil record. Previously, the oldest known fossils of hard-bodied animals were from two reef-dwelling organisms that lived around 550 million years ago.

Researchers have identified controversial fossils of soft-bodied animals that date to the latter part of the Ediacaran period between 577 and 542 million years ago.

The research was funded by the National Science Foundation's (NSF) Division of Earth Sciences.

Really no time. Rockets, kids, daycare, Avrora in kindergarten, lyuda's school. Feel lucky I have time to even post at all.

Wednesday, August 11, 2010

Researchers have found a primitive Earth mantle reservoir on Baffin Island in the Canadian Arctic. Geologist Matthew Jackson and his colleagues from a multi-institution collaboration report the finding--the first discovery of what may be a primitive Earth mantle--this week in the journal Nature.

The Earth's mantle is a rocky, solid shell that is between the Earth's crust and the outer core, and makes up about 84 percent of the Earth's volume. The mantle is made up of many distinct portions or reservoirs that have different chemical compositions.

Scientists had previously concluded that the Earth was slightly older than 4.5 billion years old, but had not found a piece of the Earth's primitive mantle.

Until recently, researchers generally thought that the Earth and the other planets of the solar system were chondritic, meaning that the mantle's chemistry was thought to be similar to that of chondrites--some of the oldest, most primitive objects in the solar system. Assuming a chondritic model of the Earth, a piece of the primitive mantle would have certain isotope ratios of the chemical elements of helium, lead and neodymium.

The model that the Earth was chondritic was called into question with a discovery five years ago by a team at the Carnegie Institution of Washington, which suggested the ratio of neodymium on Earth was higher than what would be expected if the Earth were indeed chondritic.

That finding changed the neodymium ratio expected in the primitive mantle and in turn, changed where researchers should be looking to find evidence of a primitive mantle. According to the lead author, Matthew Jackson, "We had been looking under the wrong rock."

Since many of the ancient rocks have melted over time, finding a piece of the primitive mantle means studying lavas. Lavas retain the same isotopic composition of the rocks that have melted into the lava. Therefore, testing the lava's composition is identical to testing the original rock's composition.

When the assumption about the neodymium ratio was altered, Jackson and his colleagues knew they should take a look at lava samples from Baffin Island, since those samples contained the correct ratios of helium and neodymium. They discovered that the lavas also had the correct ratio for lead. The lead isotopes suggest that the samples from Baffin Island date the lava's mantle source reservoir to between 4.55 and 4.45 billion years old, only a little younger than the age of the Earth. The lava sample comes from an ancient rock that melted 62 million years ago.

When the researchers studied the composition of the lava found at Baffin Island, they discovered that the sample had the correct ratios of all three chemical elements--helium, lead, and the new non-chronditic neodymium ratio. This discovery suggests that the sample from Baffin Island is the first evidence for the oldest mantle reservoir.

This study challenges the idea that the Earth has a chondritic primitive mantle and according to Matthew Jackson is, "suggesting an alternative." One possibility, according to Jackson, is that "the early Earth went through a differentiation event and the Earth's crust was extracted from the early mantle and is now hidden in the deep earth; the hidden crust and the mantle found on Baffin Island would sum to chondritic."

The evolutionary stories of the Swiss Army Knife and the Big Mac just got a lot longer. An international team of scientists led by Dr. Zeresenay Alemseged from the California Academy of Sciences has discovered evidence that human ancestors were using stone tools and consuming meat from large mammals nearly a million years earlier than previously documented. While working in the Afar Region of Ethiopia, Alemseged's "Dikika Research Project" team found fossilized bones bearing unambiguous evidence of stone tool use—cut marks inflicted while carving meat off the bone and percussion marks created while breaking the bones open to extract marrow. The bones date to roughly 3.4 million years ago and provide the first evidence that Lucy's species, Australopithecus afarensis, used stone tools and consumed meat. The research is reported in the August 12 issue of the journal Nature.

[...]

Although the butchered bones may not look like particularly noteworthy fossils to the lay person, Alemseged can hardly contain his excitement when he describes them. "This find will definitely force us to revise our text books on human evolution, since it pushes the evidence for tool use and meat eating in our family back by nearly a million years," he explains. "These developments had a huge impact on the story of humanity."

Until now, the oldest known evidence of butchering with stone tools came from Bouri, Ethiopia, where several cut-marked bones were dated to about 2.5 million years ago. The oldest known stone tools, dated to around the same time, were found at nearby Gona, Ethiopia. Although no hominin fossils were found in direct association with the Gona tools or the Bouri bones, an upper jaw from an early Homo species dated to about 2.4 million years ago was found at nearby Hadar, and most paleoanthropologists believe the tools were made and used only by members of the genus Homo.

The new stone-tool-marked fossil animal bones from Dikika have been dated to approximately 3.4 million years ago and were found just 200 meters away from the site where Alemseged's team discovered "Selam" in 2000. Dubbed "Lucy's Daughter" by the international press, Selam was a young Australopithecus afarensis girl who lived about 3.3 million years ago and represents the most complete skeleton of a human ancestor discovered to date.

Tuesday, August 10, 2010

The Gondwana supercontinent underwent a 60-degree rotation across Earth's surface during the Early Cambrian period, according to new evidence uncovered by a team of Yale University geologists. Gondwana made up the southern half of Pangaea, the giant supercontinent that constituted the Earth's landmass before it broke up into the separate continents we see today. The study, which appears in the August issue of the journal Geology, has implications for the environmental conditions that existed at a crucial period in Earth's evolutionary history called the Cambrian explosion, when most of the major groups of complex animals rapidly appeared.

The team studied the paleomagnetic record of the Amadeus Basin in central Australia, which was part of the Gondwana precursor supercontinent. Based on the directions of the ancient rock's magnetization, they discovered that the entire Gondwana landmass underwent a rapid 60-degree rotational shift, with some regions attaining a speed of at least 16 (+12/-8) cm/year, about 525 million years ago. By comparison, the fastest shifts we see today are at speeds of about four cm/year.

This was the first large-scale rotation that Gondwana underwent after forming, said Ross Mitchell, a Yale graduate student and author of the study. The shift could either be the result of plate tectonics (the individual motion of continental plates with respect to one another) or "true polar wander," in which the Earth's solid land mass (down to the liquid outer core almost 3,000 km deep) rotates together with respect to the planet's rotational axis, changing the location of the geographic poles, Mitchell said.

The debate about the role of true polar wander versus plate tectonics in defining the motions of Earth's continents has been going on in the scientific community for decades, as more and more evidence is gathered, Mitchell said.

In this case, Mitchell and his team suggest that the rates of Gondwana's motion exceed those of "normal" plate tectonics as derived from the record of the past few hundred million years. "If true polar wander caused the shift, that makes sense. If the shift was due to plate tectonics, we'd have to come up with some pretty novel explanations."

Whatever the cause, the massive shift had some major consequences. As a result of the rotation, the area that is now Brazil would have rapidly moved from close to the southern pole toward the tropics. Such large movements of landmass would have affected environmental factors such as carbon concentrations and ocean levels, Mitchell said.

"There were dramatic environmental changes taking place during the Early Cambrian, right at the same time as Gondwana was undergoing this massive shift," he said. "Apart from our understanding of plate tectonics and true polar wander, this could have had huge implications for the Cambrian explosion of animal life at that time."

uh. Yeah. To say the least. If it did this, I'd be very surprised if there wasn't a lot of volcanism. 60 degrees though?!

The U.S. government should lead development of a nuclear thermal propulsion system for a future Mars mission and leave new heavy-lift launchers to commercial entities, Space Exploration Technologies (SpaceX) says.

The company, which until now has focused mostly on development of vehicles to transport cargo and humans to low Earth orbit (LEO), believes its Falcon 1 and Falcon 9 launchers could be evolved into a heavy-lift family that will provide the basis for a Mars-capable architecture.

For the transition from Earth to Mars, however, SpaceX believes nuclear thermal is the preferred propulsion means for the piloted aspect of the mission, while solar-electric power could be used to transport supplies.

The U.S. government “should take the lead on nuclear and commercial industry should take the lead on building heavy-lift launch vehicles,” Markusic says. “Low-level propulsion technology research and development should be government-led, with a transition to flight development in 2025.”

Markusic’s call flies in the face of SpaceX’s usual advocacy for industrially driven competition and Commercial Orbital Transportation Services (COTS)-like procurement. However, he says “the government should only lead the propulsion element development where there is no existing commercial capability, or a high risk of capital loss.”

For cargo to Mars, SpaceX’s architecture suggests tugs powered by clusters of solar-electric powered thrusters. The 100-kw. tugs each would carry around 4 metric tons of payload and take 390 days for the round trip.

The plan envisages a fleet of up to 10 tugs rotating between LEO and Mars orbit, with vehicles being serviced and turned at a terminus based on the International Space Station.

For landing and ascending on Mars or its moon Phobos, SpaceX is proposing a liquid oxygen (Lox)/methane powered propulsion system capable of delivering a payload of approximately 35 metric tons. In-situ derived methane could be used for fuel, while existing engines now in development by ATK or Xcor Aerospace could provide the basis for initial units.

SpaceX’s long-discussed Merlin 2 Lox/rocket propellant-fueled engine, capable of a projected 1.7 million lb. of thrust at sea level and 1.92 million lb. in a vacuum, would provide the power for the Falcon X and XX heavy launch vehicles.

Slated to be introduced on more capable variants of the Falcon 9 Heavy, the Merlin 2 “could be qualified in three years for $1 billion,” Markusic says.

Three Merlin 2s would power the first stage of Falcon X, a 300-ft. plus tall vehicle capable of placing 38,000 kg. in LEO.

A growth development, dubbed Falcon X Heavy, would employ nine engines clustered in three cores. Collectively these would generate 10.8 million lb. of thrust at liftoff and boost 125,000 kg. to orbit. The ultimate launch vehicle, the Falcon XX, stands as tall as the Saturn V, is configured with six engines in a single core and is designed to lift 140,000 kg. to LEO.